1. Field of the Invention
The present invention relates to a patient sealing interface for use as part of an apparatus for supplying a flow of respiratory gases to a user.
2. Description of the Related Art
It is known to provide a flow of respiratory gases to a user via an interface such as a face mask to relieve a number of ailments—for example sleep apnea or snoring. One problem with supplying a flow of gases to a user via an interface such as a face mask is that it can be difficult to form a good seal between the mask and the face. The mask is often held in place against the user's face by head gear worn on the user's head. In use, the head gear may be over tightened so that the mask is pressed uncomfortably onto the user's face. Alternatively the headgear may be under tightened or applied to the user's head too loosely, preventing the formation of an effective seal between the mask and user's face.
Prior art face masks have attempted to improve the seal between the user's face and the mask and make the sealing interface with the user more comfortable. U.S. Pat. No. 7,308,895 describes a mask assembly having a seal outer sheath and inner cushion. The inner cushion has a raised nasal bridge portion which results in a more flexible seal contact on the bridge of the user's nose. The raised nasal bridge portion is formed by a cut out portion of the inner cushion, the cut-out being on a mask body side of the cushion.
U.S. Pat. No. 6,112,746 describes a nasal mask cushion for sealing a nasal mask to a user's face. The cushion has a first membrane and a second membrane. The second membrane contacts a user's face when in use. The second membrane is thinner than the first membrane and is spaced apart from the first membrane when the mask is not in use. The second membrane is spaced from the first membrane by a greater distance in the nasal bridge region than in the cheek region.
In this specification where reference has been made to patent specifications, other external documents, or other sources of information, this is generally for the purpose of providing a context for discussing the features of the invention. Unless specifically stated otherwise, reference to such external documents is not to be construed as an admission that such documents, or such sources of information, in any jurisdiction, are prior art, or form part of the common general knowledge in the art.